SPb-Giproshakht, Saint-Petersburg, Russia:

M. P. Talerov, Leading Engineer, Candidate of Engineering Sciences

Saint-Petersburg Mining University, Saint-Petersburg, Russia:
V. I. Bolobov, Professor, Doctor of Engineering Sciences, Boloboff@mail.ru

Using the developed procedure, in terms of picks BTK53, BGF22 and BSR111 with sintered carbide inserts of different diameters (d = 12 mm, 15 mm and 19 mm, respectively) and different geometry of the cutting part, it is studied how the contact strength P_k and abrasion index а of rocks influence the prefailure life of the picks (cutting length L) in typical geological conditions of operation of road header machines. It is shown that the diameter of the sintered carbide inserts is the influencing parameter of loading and can be assumed a sufficiently objective geometrical characteristic of loading of picks. The results of the design analysis are presented as the plots L = f(P_k, а) with two zones distinguishable in case of all models of the tested picks. In the first zone, typical for weak rocks (P_k < 200…300 MPa), irrespective of abrasiveness, or for weakly abrasive rocks (а > 19…20 mg), irrespective of strength, failure of a pick takes place when the wear limit of the hold head is achieved with the total exposure of the sintered carbide insert and its breaking out along the contact of the insert end and the holder. In the second zone, the cutting length of a pick is governed by the damage of the sintered carbide insert as a result of exposure by a certain critical value at which stresses induced in the insert under a peak force exceed the ultimate strength of carbide material. The zone conformable with the insert damage due to the cyclic stresses (fatigue) is not revealed. The design analysis results are confirmed by the data of industrial tests of the picks.

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